I know this most likely won't be read but, My only real problem so far is his over specialisation, as of right now he only really uses his doujutsu, swords and speed and this results in his physical strength and defence lacking as well as causes him to be more predictable in battle. I would recommend giving the mc a bloodline like Jugo's (Naruto) or an ability such as Crush magic (Fairy Tail) even the boost ability of Boosted Gear (High School DxD).
heavenlydogdog